Pollution prevention seeks to change production processes to reduce the generation or use of environmentally harmful substances. Measured on their own terms, pollution prevention programs have often been successful. However, the impact of pollution prevention on occupational exposures is largely unknown. Anecdotal evidence suggests that some pollution prevention programs have decreased occupational exposures, while others have exacerbated such exposures. Unfortunately, there is a lack of scientifically based knowledge to inform the pollution prevention choices of firms and policymakers who seek to avoid exacerbating occupational exposures. No systematic study of the impact of any particular pollution prevention program on occupational chemical exposures has been undertaken. An obstacle to undertaking of such a study is the lack of methods to assess the impacts of pollution prevention activities on occupational exposures especially in the absence of industrial hygiene monitoring data. The proposed study is designed to address this lack. It uses procedures for retrospective exposure assessment that are well-established in industrial hygiene and occupational epidemiology to evaluate the impact of pollution prevention on occupational exposures. The new method will be validated in a case study in which comprehensive monitoring data are available. The specific aims are: to develop comprehensive exposure assessments with and without the use of monitoring data; to determine whether the two methods of assessment produce similar rankings of exposure by occupational title; and to determine whether the two estimates of exposure suggest similar conclusions as to the impact of pollution prevention on occupational exposures at the case study facility. Because pollution prevention programs often involve chemical substitutions, it is necessary to compare the relative risks of different exposures. To weight exposure levels within each occupational title, exposure levels will be divided by the NIOSH recommended exposure limit (REL). An exposure severity score will be calculated for each occupational title by summing REL-weighted exposures across chemicals. Student's t-test will be used to test a null hypothesis that the process changes implemented for the purpose of pollution prevention had no significant impact on occupational exposure. These procedures will be performed without the use of air monitoring data and then repeated using the data. Results will be compared for agreement using a kappa statistic.